1. Roman Roads
Pathway to an Empire

2. The first Roman road, built in 312BCE.
Via Appia
The first Roman road, built in 312BCE.

3. Why did the Romans need roads?
First and foremost—military needs. The army needs to move its supplies (impedimenta) and its camp materials (castra) many hundreds of miles. Roads provide speed and ease of travel for Rome’s many legions.
Economic needs - in order to bring supplies, money, and commerce to places, Rome needs an easy and obvious way to get food, construction material, and other supplies to the city.
Governing needs - a government needs fast information and communication to effectively rule their land. Roads promote faster, and more frequent communication between towns, rulers, armies, and peoples.

4. The Map of Roman Roads: http://www.ancient.eu/map_pelagios/

5. Construction How to build a lasting road.
On the right: the Via Appia in common use in Rome today.

6. Who built the roads?
Nearly always soldiers.

8. Roman Roads were a series of layers
There were anywhere from 4-8 steps when making a Roman road, but we will look at the most common one.
First, Romans needed to make sure that they were building a road that was straight, level, and the correct length.
Roads that were flat, straight, and uniform would be better maintained, easier for people and animals to travel on, and faster. (The fastest path between two points is a straight line).
They accomplished this using measuring rods (basically, a yard stick) and a tool called a groma

9. Tools of the trade
A groma has four weights on each end of the cross on its top.
When the tool is flat, the weights form a 90 degree angle, ensuring that the road is flat in all directions.

10. First step: dig a trench
Romans dug a “fossa” and laid curbstones on either side.
Many roads also had drainage ditches on each side of the road.

11. Next steps: fill in the layers of the road
Bottom layer: compacted sand or earth - the pavimentum
Base layer: large flat (or crushed and flattened) rocks mixed with cement- the statumen
Next layer: coarse (rough and bumpy) concrete - the rudus
Next layer: smooth and thin concrete - the nucleus
Top layer: shaped, large rocks fit in snugly, shaped like a hunch - the summa crusta

13. Curvature of Roman roads
Effectively and cheaply drains the road.

14. Why have so many layers?
The layers of the road act sort of like a sponge: they can withstand lots of weight and abuse from all the traffic, but still retain its shape.
The layers of concrete and rock also resist erosion from water, shifting earth, animal and plant destruction, and other natural climatic effects.
The top layer is easy to maintain—just pull out any broken/warped stones, and replace with a new one.

15. Stubborn Romans
The Romans, when building roads, generally did not avoid obstacles like swamps, mountains, cliffs, and rivers.
They usually went over or through them by any means.
One prominent example is in Tarracina, where the emperor Trajan had his workers dig 100 feet down into pure rock, in order to keep the road straight.

17. Pathfinding with milestones
Roman roads were built with milestones (miliaria) that gave geographical information—most importantly, how far away the Roman Forum is.
These miliaria enabled travelers to find their way to Rome from nearly any part of the Roman Empire.
The milestones also listed nearby cities in a list called an itinerium.